JP2002-99386A1 discloses a system for scrolling a screen by using a visual line of a user. The system detects a direction of a visual line of a user based on an image captured by a camera, and detects a position on a screen of a display device being viewed by the user. When the visual line reaches an edge of the screen, a scroll arrow is displayed on the edge of the screen, and when the visual line moves out of the screen after the scroll arrow is displayed, the screen is scrolled.
In the system of JP2002-99386A1, when a visual line is moved and a position of an edge of the screen being viewed changes, scrolling of an image stops. For example, when a large image (such as a map) is displayed and a position a user wishes to view is approaching, a user scrolls an image minutely from vertically to horizontally or from horizontally to vertically to display the desired position. However, in the system of JP2002-99386A1, each time a direction of view changes, scrolling of an image is stopped, which requires time to scroll to the desired position.